Inventory Rotation and First-Expired-First-Out in a Small Lab

For dated research material, rotate first-expired-first-out (FEFO): the container with the earliest expiry or retest date is used first, whatever order it arrived in. Make that the easy choice by arranging shelves so the next container to use is always at the front, write receipt and opening dates on every container, and review slow-moving stock monthly so nothing reaches its date unnoticed. Everything else is detail.

This sits next to the lot register but is a different job. The register records what exists and where. Rotation governs what physically happens at the shelf, which container a person picks up when they reach into the freezer, and that is where most dated stock is actually lost.

FIFO and FEFO, and why the second is correct for dated material

First-in-first-out (FIFO) uses stock in the order it arrived. First-expired-first-out uses it in date order. WHO defines FEFO as a procedure ensuring that stock with the earliest expiry date is distributed or used before an identical item with a later date ^[2]. The two orders are identical until a supplier ships an older lot after a newer one, or until two suppliers' lots of the same material sit side by side. At that point FIFO uses the fresher container first and leaves the older one to date out.

Regulated distribution settles which rule applies. EU Good Distribution Practice says stock should be rotated according to FEFO, with exceptions documented, and that products nearing their expiry should be withdrawn from saleable stock physically or by equivalent electronic segregation ^[1]. WHO's storage guidance repeats the FEFO principle ^[2]. The US manufacturing rule states the same idea in older wording: a procedure under which the oldest approved stock is distributed first, with deviation allowed only if temporary and appropriate ^[3]. None of these binds a small research lab, but all of them reach the same answer for the same reason.

Research material often carries a retest date rather than an expiry. ICH Q1A(R2) defines a retest date as the point after which material should be examined to confirm it still meets specification ^[5]. For rotation it works the same way: the earliest retest date goes first. The difference comes at the date, where retest material can be retested and redated by whoever holds the stability basis, and expired material cannot.

A physical arrangement that makes rotation automatic

Rotation that depends on someone reading dates in a cold, open freezer fails, because people take the nearest container and close the door. The arrangement has to make the nearest container the right one.

• One material per box or rack, one lot per row where possible, with the date written large on the outside of the box.
• Earliest date at the front or left; new stock always goes in at the back or right, never on top of the old.
• Opened containers in a clearly marked "use first" position at the front, since their usable life is shorter than the label date.
• A short-dated zone in the same unit, for anything within roughly 90 days of its date.
• A separate, labelled hold area for quarantined, excursion-affected or expired material, so it cannot be picked up by mistake ^[1].
• In a chest freezer, where depth defeats front-to-back order, use labelled baskets or racks you can lift out, ordered by date.

CDC's vaccine guidance uses routine temperature checks as the moment to tidy the unit, reorganise misplaced items and remove expired stock ^[4]. The same habit suits a research freezer. Whenever the door is open for a check anyway, glance at the front row.

Recording receipt and opening dates

Rotation needs three dates for each container, and only one of them is printed by the supplier. The printed expiry or retest date sets the order. The receipt date lets you trace a container back to its delivery and tells you how long it has sat. The opening date starts whatever in-use limit your procedures set, and it usually matters more than the printed date once a container is open.

1. At goods-in, write the receipt date on the container or its box, next to the internal identifier.
2. Record the printed date in the register, stating whether it is an expiry or a retest date.
3. At first opening, write the opening date and initials on the container.
4. Where you set an in-use limit, write the resulting use-by date beside it, so no one has to calculate it later.
5. Open one container of a given material at a time, so there is only ever one partly used container to use up first.

Identifying slow-moving stock before it dates

Most dated-out material was not forgotten; it was simply bought faster than it was used. The fix is a scheduled look ahead. CDC counts stock at least monthly, checking dates during the count and removing anything expired ^[4]. WHO expects stock records to be updated with every movement and reconciled against a physical count at defined intervals, with the root cause of any discrepancy found ^[2]. For a small lab, one monthly review does both.

• Filter the register for anything within 90 days of its printed date.
• For each item, ask whether use is planned before that date. If not, decide now: bring the work forward, pass it to a colleague who will use it, arrange a retest if it is retest-dated and the supplier can support it, or plan disposal.
• Check the count against the register and investigate mismatches, since a missing container and an unrecorded use look the same until someone asks ^[1].
• Note what dated out and why. Repeated waste of the same material is a buying signal: smaller pack sizes or more frequent orders.

Disposal decisions and documenting them

When material passes its expiry date, or its retest date with no retest, it leaves usable stock. Move it to the hold area first, then dispose of it by the method its safety data sheet and your institution's waste rules require. Do not keep it on the working shelf "just in case". Broken or damaged containers leave usable stock the same way ^[2]. Before discarding anything, check whether a peptide really expires, and what the date means, so the decision is based on what the date actually represents, not on its being a tidy cut-off.

The disposal record is part of the batch records traceability depends on. Each one should give the internal identifier and supplier lot, the date, the reason (expired, retest date passed, excursion, damaged, contaminated), the method and the initials of the person. Mark the register row disposed rather than deleting it; work that used the container earlier still points at that row.

A minimum workable system without software

A small lab can run FEFO with a marker pen, a spreadsheet and a calendar reminder.

The one habit that holds it together is putting new stock behind old at the moment of receipt. Everything else can slip for a week and be caught at the monthly review; a delivery pushed in front of older stock is how material dates out while the register looks perfectly tidy.